Bleeding Heart Baboon
The gelada (Theropithecus gelada), sometimes called the bleeding-heart monkey, bleeding heart baboon or the gelada baboon, is a species of Old World monkey found only in the Ethiopian Highlands, with large populations in the Semien Mountains. Geladas are actually not baboons but members of their own genus Theropithecus. Like its close relatives the baboons (genus Papio), it is largely terrestrial, spending much of its time foraging in grasslands.
The gelada is large and robust. It is covered with buff to dark brown, coarse hair and has a dark face with pale eyelids. Its arms and feet are nearly black. Its short tail ends in a tuft of hair. Adult males have a long, heavy cape of hair on their backs. The gelada has a hairless face with a short muzzle that is closer to a chimpanzee's than a baboon's.
It can also be physically distinguished from a baboon by the bright patch of skin on its chest which gives rise to the “bleeding-heart” monikers. This patch is hourglass-shaped. On males, it is bright red and surrounded by white hair; on females, it is far less pronounced. However, when in estrus, the female's patch will brighten, and a "necklace" of fluid-filled blisters forms on the patch. This is thought to be analogous to the swollen buttocks common to most baboons experiencing estrus.
The gelada has several adaptations for its terrestrial and graminivorous (grass-eating) lifestyle. It has small, sturdy fingers adapted for pulling grass and narrow, small incisors adapted for chewing it. The gelada has a unique gait, known as the shuffle gait, that it uses when feeding. It squats bipedally and moves by sliding its feet without changing its posture. Because of this gait, the gelada's rump is hidden beneath and so unavailable for display; its bright red chest patch is visible, though.
Geladas are the only primates that are primarily graminivores and grazers – grass blades make up to 90% of their diet. They eat both the blades and the seeds of grasses. When both blades and seeds are available, geladas prefer the seeds. They also eat flowers, rhizomes and roots when available, using their hands to dig for the latter two. They also consume herbs, small plants, fruits, creepers, bushes and thistles. Insects can be eaten, but only rarely and only if they can easily be obtained. During the dry season, grasses are eaten less and herbs are preferred. Geladas consume their food more like ungulates than primates, and can chew their food as effectively as zebra.
Geladas live in a complex multilevel society similar to that of the hamadryas baboon. The smallest and most basic groups are the reproductive units, which are made up of one to twelve females, their young and one to four males, and the all-male units, which are made up of two to fifteen males. The next level of gelada societies are the bands, which are made up of two to twenty-seven reproductive units and several all-male units. Herds consist of up to 60 reproductive units that are sometimes from different bands and last for short periods of time. Communities are made of one to four bands whose home ranges overlap extensively. A gelada can typically live to around 20 years old.
When more than one male is in a unit, only one of them can mate with the females. The females in the group together can have power over the dominant male. When a new male tries to take over a unit and overthrow the resident male, the females can choose to support or oppose him. The male maintains his relationship with the females by grooming them rather than forcing his dominance, in contrast to the society of the hamadryas baboon. Females accept a male into the unit by presenting themselves to him. Not all the females may interact with the male. Usually, one may serve as his main partner. The male may sometimes be monopolized by this female. The male may try to interact with the other females, but they are usually unresponsive.
Researchers from the University of the Free State (UFS) in South Africa, while observing gelada monkeys during field studies, discovered that the monkeys were capable of 'cheating' on their partners and covering up their 'infidelity'. A non-dominant male would mate surreptitiously with a female, suppressing their normal mating cries so as not to be overheard. If discovered, the dominant male would attack the miscreants in a clear form of punishment. It is the first time that evidence of the knowledge of cheating and fear of discovery has been recorded among animals in the wild. Dr Aliza le Roux of the Department of Zoology and Entomology at the university believes that dishonesty and punishment are not uniquely human traits, and that the observed evidence of this behaviour among gelada monkeys suggests that the roots of the human system of deceit, crime and punishment lie very deep indeed.
Mixed-species association was observed between solitary Ethiopian wolves and geladas. According to the study's findings, gelada monkeys would not typically move on encountering Ethiopian wolves, even when they were in the middle of the herd—68 percent of encounters resulted in no movement and only 11 percent resulted in a movement of greater than 10 meters. In stark contrast, the geladas always fled great distances to the cliffs for safety whenever they encountered aggressive domestic dogs.
